「有邊讀邊學生物英文」是慈濟大學MOOCs線上課程，目的在提供高三升大一生醫領域相關學系學生、以及對生醫領域有興趣的社會人士一個學習專業字首與字根的法門。
生醫領域剛進入時常遇到的問題就是：生物、醫學乃至化學領域的專業字彙極多。但這些專業字彙，大多是由拉丁文與希臘文構成的字首（prefix）與字尾（suffix）組成，本課程由個別字首與字尾的介紹，配合舉例與作業，使學習者能逐漸熟悉專業字彙的組成，甚至在未來遇到不認識的專業字彙時，能夠「有邊讀邊」，猜個八九不離十！
"English for Biology Majors" is a MOOCs course from Tzu Chi University. Using lots of examples to teach prefix and suffix in biomedical terms. All you need is 15 minutes everyday to learn them all !

2016年5月3日 星期二

What is the relationship between halogens and salts?

In Lesson 17-4, we learned that functional groups containing chlorine (Cl) are using the prefix hal(o)-. As a matter of fact, fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At) are called the halogens or halogen elements collectively.

However, we learned that the suffix hal(o)- meaning sea or salt in Lesson 18-2. Are they using the same prefix? Why is that?

The reason why elements fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At) are called the halogens is because when they react with metals they produce a wide range of salts, including calcium fluoride, sodium chloride (common salt), silver bromide and potassium iodide. Therefore, they are name halogens, meaning 'salt-producing'. The suffix -gen means 'produce', which we learned in Lesson 16-5.

This name was suggested by Swiss chemist Jöns Jakob Berzelius in 1842. However, the term halogen was created by Johann Salomo Christoph Schweigger at 1811. It was suggested for naming chlorine at the time, but it was not used. Later, the term was used by calling all of the element of group 17 -- including chlorine.